Environmental Chemistry and Engineering

Coating improves paper properties and can be applied in production and converting of paper. The main purpose of this research is to investigate the effect of biodegradable coatings on physical and mechanical properties of printing paper. The coatings were composed of kaolin clay, ground calcium carbonate, dispersant and different ratios of polyvinyl acetate, lactic acid and distilled water. Five formulations were made and the formulations had 30% or 50% solid content. After coating using bar method, the base papers were dried and calendered. Physical, barrier and mechanical properties were examined for each sample. The pigments and binders can be seen in the field emission scanning electron microscope (FESEM) view graphs. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of binders and their reactions. The results were obtained from ANOVA and Duncan tables. The coating treatments improved many of the mechanical properties (tear and burst) but had an adverse effect on the mechanical indexes. All measured optical properties (brightness, opacity and yellowness) were improved due to coating. Water absorption values (Cobb) were increased in the many treatments, but it was reduced in one formulation in order to more binders. The three combinations of coatings with 50% solid content reduced roughness which had correlation with improvement of barrier properties. The best barrier properties were found in the 3 combinations. The third suspension with 50% solid had the best droplet contact angle and contact angle change over time. The results showed that our slurry formulations decreased air permeability and water vapor transmission rate (WVTR) in the coated papers.

Clay particles on the coated paper.

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